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Aug
18
2008

Xbee Modules as Proximity Sensors

For this project I want to use the Xbee modules, not only to allow the glasses to share data with each other, but also as proximity sensors. To test whether that this is a viable option, I placed two Xbee modules at specific distances from each other and took signal strength measurements over a minute. I averaged these values and graphed them.

One module was connected via USB to a computer so I could collect the antenna strength data directly to the computer. I wrote a short python program to assist me in the collection of this data.
Signal Strength of Xbee modules
According to this investigation, I am a little worried about using the Xbees to determine proximity. I tested the Xbee modules in an open space in a clear line of sight from each other and the signal strength values were very inconsistent. A bar situation will be much more complex because the space will contain obstructions such as people and walls. Additionally, I did not test the Xbee modules within the glasses. I plan to include capacitance sensors within these glasses which means that the glasses will be covered with a clear conductive film. The problem with this strategy, even if it works well with the capacitance sensors, is that the film may dampen the signals sent between the glasses.

In a perfect world, it is my hope to eventually find a way to accurately measure distance between glasses so I can use triangulation to map out the location and movement of the glasses within the bar space. Currently, I can tell whether two glasses are within 5 feet of each other through signal strength. At the moment I plan to integrate close proximity events like this into my project.

I have not found a way to determine signal strength between the modules without putting the Xbees into command mode. This is incredibly undesirable because I want to be constantly collecting and sharing accelerometer data and I can not do this when the Xbee is in command mode.

This entry was posted on Monday, August 18th, 2008 at 6:31 pm and is filed under documentation, proximity, transciever. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.

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  • What is it?

    The Sociable Pint investigates the use of networked objects, not to further an impersonal trajectory of media, but to encourage and augment face-to-face conversation.

    Through the introduction of Pint-to-Pint (P2P) networking, bar glasses become social objects themselves, mapping themselves onto the existing network of people, in turn inserting a new layer of sociability within the space.

    By networking pint glasses capable of sensing, recording, and interpreting gestural data, the glasses can collectively provide direct intervention onto the social fabric within the bar space.

  • Why?

    Sociable media have introduced a shift in how we communicate by providing more intuitive technological interfaces. But as these technologies provide a new salience within existing social frameworks and appropriate the practice of face-to-face conversation toward new media platforms it becomes imperative to not only question sociable media's effect on face-to-face conversation, but to design sociable media which move in the opposite direction: to encourage and augment face-to-face conversation.

  • How?

    Sensors embedded within each glass collect data indicative of how each glass is being used. Among other actions, the glasses can sense if they are being held, if they are being "cheersed," how they are being tilted, if they are being ignored, as well as their relative proximity to other glasses, etc. Through the interpretation of sensor data, each glass has the ability to send information via wireless transceivers to the other glasses in order to gain access to the entire system of networked pint glasses.

    In addition to reciprocating information among the glasses, each glass expresses itself through an RGB LED embedded in each glass. Glasses which are used in similar ways, glasses which are in close proximity of each other, and glasses which are "cheersed" together exhibit behaviors intentionally designed to induce conversation between the bar patrons.

    Data from the entire population of pint glasses is collected by a central computer. Images representing the interpretation of this data are displayed onto the televisions within the bar, providing additional feedback to the bar patrons correlating to the gestural culture of the bar space.

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